<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link rel="stylesheet" href="font-awesome-4.7.0/css/font-awesome.min.css"/>
    <style>
        .item{
            background-color:#dddddd;
        }
        .item .a:hover{
            color: red;
        }
        /*.item .b:hover{*/
            /*color: green;*/
        /*}*/
        .item:hover .b{
            color: yellow;
        }
    </style>
</head>
<body>
    <div class="item">
        <div class="a">
            <i class="fa fa-superpowers" aria-hidden="true"></i>
        </div>
        <div class="b">绿色</div>
    </div>
</body>
</html>